evaluation of the feasibility of the use of bamboo as potential … · 2019-03-20 · concrete...

Osuji and Kayode-Ojo, 2019 9

Nigerian Journal of Environmental Sciences and Technology (NIJEST)

www.nijest.com

ISSN (Print): 2616-051X | ISSN (electronic): 2616-0501

Vol 3, No. 1 March 2019, pp 9 - 17

Evaluation of the Feasibility of the Use of Bamboo as Potential

Reinforcement in Concrete Beams

Osuji S. O.1 and Kayode-Ojo N.

2,*

1,2Department of Civil Engineering, University of Benin, Benin City, Edo State, Nigeria

Corresponding Author: *[email protected]

ABSTRACT

This study presents the evaluation of the feasibility of using bamboo as a potential reinforcement in

concrete beams. To achieve this, absorption test, tensile tests on the bamboo; compressive test on

concrete cubes were conducted. Three-point bending tests on concrete beams reinforced with

bamboo were performed to identify their behaviour compared to steel reinforced concrete

members. The result for the absorption test indicated that water absorption of bamboo is quite

high. The bamboo absorbed about 25% of water of its saturated weight in just 24 hrs and increased

number of nodes brought about increased absorption of water. It also showed that the bamboo

from the top part of the culm absorbed more water than those from the bottom of the culm, with an

increase of about 9%. For the tensile tests all the bamboo specimens showed brittle failure at node,

making the node the most critical section for failure under tensile stresses, which was also verified

in the beam tests. The yield stress was 56.80 N/mm2. In general, the test results indicated that

bamboo reinforcement enhanced the load carrying capacity by approximately 200%.

Keywords: Bamboo, Three-point bending tests, Absorption, Tensile tests, Compressive tests

1.0. Introduction

In most countries, concrete is widely used as the foundation for the infrastructure. Concrete is used

largely because it is economical, readily available and has suitable building properties such as its

ability to support large compressive loads. However, the use of concrete is limited because it has low

tensile strength. For this reason, it is reinforced, and one of the more popular reinforcing bars (rebar)

is steel (Salau et al., 2012). Steel has a relatively high tensile strength, as high as 792 N/mm2,

complementing the strength of concrete. It is available and affordable in most developed countries but

unfortunately not in all parts of the world. In many countries, none or very little steel reinforcement is

used in construction, which is evident from the crumbling of buildings.

Steel reinforcement at some point may no longer be available. Even today there exists a need for more

economical and readily available substitute reinforcements for concrete. In some parts of the world

many buildings are constructed only with concrete or mud-bricks. This is dangerous in case of seismic

activity. These buildings have little hope of standing in the case of an earthquake. Steel reinforcement

would be an ideal solution, but cost is a considerable problem. Scientists and engineers are constantly

seeking for new materials for structural systems; the idea of using bamboo as possible reinforcement

has gained popularity (Siddhpura et al., 2013).

The energy necessary to produce 1 m3 per unit stress projected in practice for materials commonly

used in civil construction, such as steel or concrete, has been compared with bamboo. It was found

that for steel it is necessary to spend 50 times more energy than for bamboo. The tensile strength of

bamboo is very high and can reach 370 N/mm2 (Bhonde et al., 2014). This makes bamboo an

alternative to steel in tensile loading applications as the ratio of tensile strength to specific weight of

bamboo is six times greater than that of steel.

Nigerian Journal of Environmental Sciences and Technology (NIJEST) Vol 3, No. 1 March 2019, pp 9 - 17

10 Osuji and Kayode-Ojo, 2019

Recently, in the attention and response to global warming issues and sustainable society, the use of

natural materials for manufacturing has become more active. Bamboo’s low cost, fast growing, and

broad distribution of growth, is expected to contribute significantly to earthquake-resistant

construction and seismic retrofit technology in the developing countries (Steinfeld, 2001). In concrete,

reinforcement is put in place to provide tensile strength, a property that concrete lacks. Therefore, if

bamboo is to be used as concrete reinforcement, it is necessary to understand how bamboo behaves in

tension.

The aim of this study is to determine the feasibility of using bamboo as reinforcement in concrete

beams and will be providing a preliminary contribution toward the collection of the mechanical

properties and behaviours of bamboo and bamboo reinforced beams. The objectives are:

i. To carry out water absorption rate test on bamboo

ii. To carry out tensile tests on bamboo

iii. To compare the elastic modulus and flexural strength of bamboo reinforced beams and steel

reinforced beams.

This study will consider the bambusa vulgaris specie, seasoned and cut into thin strips and tested

without any treatment to determine the absorption and tensile properties of the bamboo. To examine

the behaviour of the bamboo in the concrete, three-point load bending test will be conducted on

bamboo reinforced beams and the results compared with that of steel reinforced and plain concrete

beams.

This study is performed mainly for the rural areas, where bamboo is of ample amount, steel is rare,

expensive or transportation cost is high. In coastal areas, the economic condition of people is very

poor. In such type of backward area, such study may be essential for their development as well as an

assurance for low cost housing. After the study it is seen that samples constructed as aid of bamboo

can offer respectable amount of strength that can be safely used for low-cost housing.

The use of bamboo as a structural element may contribute to the reduction of material-based energy

use of a structure (Sakaray et al., 2012). Even with the rising rate of insurgency around the globe,

bamboo can be used to construct low cost but befitting structures for displaced individuals and

families. The main obstacle for the application of Bamboo as a reinforcement is the lack of sufficient

information about its interaction with concrete, strength and durability, hence the relevance of this

work cannot be over emphasized.

2.0. Materials and Methods

The bamboos used for this study were very matured and cut from the undeveloped Site B section of

the University of Benin, Benin City, Edo State in Nigeria. They were dried under the sun for thirty

days before reducing to thin strips for the tests. The following tests were carried out:

2.1. Absorption test

Bamboo like wood changes its dimension when it loses or gains moisture. Bamboo is a hygroscopic

material, tending to absorb moisture from air and surroundings (Wakchaure,and Kute, 2012). Four

different bamboo splints were taken from top and bottom portions of bamboo culm for the test as

shown in the Figure 1, with their properties listed in Table 1.



Figure 1: Absorption test specimen

Table 1: Description of absorption test specimen Specimen Property

A1a One internode (from top of culm)

A2a Two internodes (from top of culm)

B1a One internode (from bottom of culm)

B2a Two internodes (from bottom of culm)

Using the below mathematical expression the amount of water absorbed by both types of samples was

calculated.

𝑊𝑎𝑡𝑒𝑟 𝑎𝑏𝑠𝑜𝑟𝑏𝑒𝑑 (𝑔𝑚) = 𝑓𝑖𝑛𝑎𝑙 𝑠𝑎𝑡𝑢𝑟𝑎𝑡𝑒𝑑 𝑤𝑒𝑖𝑔ℎ𝑡(𝑔𝑚) − 𝐷𝑟𝑦 𝑤𝑒𝑖𝑔ℎ𝑡(𝑔𝑚) (1)

% 𝑏𝑦 𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑤𝑎𝑡𝑒𝑟 𝑎𝑏𝑠𝑜𝑟𝑏𝑒𝑑 =𝑤𝑎𝑡𝑒𝑟 𝑎𝑏𝑠𝑜𝑟𝑏𝑒𝑑 (𝑔𝑚)

𝑓𝑖𝑛𝑎𝑙 𝑠𝑎𝑡𝑢𝑟𝑎𝑡𝑒𝑑 𝑤𝑒𝑖𝑔ℎ𝑡 (𝑔𝑚) × 100 (2)

2.2. Tensile test

Tension test is the most basic type of mechanical test. It is easy to perform and relatively inexpensive

compared to other tests. The stress- strain characteristics of bamboo is derived from the results of this

tension test.

The Bamboo strips were of various lengths and thicknesses (see Table 2). The ends of the specimen

were roughed at both ends to have better grip in Universal Testing Machine. The sample strip of the

Bamboo is as shown in Figure 2.

Figure 2: Tensile test specimen

Table 2: Description of tensile test specimen Sample Node position Specimen size Cross sectional area

Length(mm) Thickness(mm) End A End B Average area(mm2)

A1t Centre 540 10 220 230 225

A2t End 540 10 220 190 205

B1t Centre 450 15 450 420 435

B2t End 450 15 420 450 435



The position of the Bamboo strip in UTM is as shown in Figure 3.

Figure 3: Bamboo strip in UTM

A stress vs strain curve was drawn from the results of the tensile test on the strip. The yield stress is

also got from the stress vs strain curve.

The equation to calculate the Modulus of Elasticity is as mentioned in Equation 3.

𝐸 = 𝜎

휀 (3)

where:

σ Stress

ε Strain

E Modulus of Elasticity

2.3. Beam tests

Since it is the purpose of this research to determine the feasibility of the use of Bamboo as

reinforcement in concrete, it is necessary to compare its behaviours to steel, which is the traditional

reinforcement. Therefore, beam designs were in accordance with BS 1881-118:1983 codes and

specifications.

The dimensions were those that would allow for practicality of testing and construction, therefore a

width of 150 mm and a depth of 150 mm was chosen for the test beam.

The next step was to determine the length of the beam. Evaluating the laboratory conditions and

desired testing set-up, a beam length of 750 mm was chosen. Figure 4 shows the final dimensions of

the test beam.

Figure 4: Beam dimension

2.4. Flexural test

The Universal Testing Machine (UTM) was used for this test. The test set-up was done according to

BS1881-118 1983.

The flexural strength 𝐹𝑐𝑓 (in N/mm2) is given by the equation:

𝐹𝑐𝑓 = (𝐹 × 𝐿)

(𝑑1 × 𝑑22)

(4)

150 mm

150 mm 750 mm



where:

F Breaking load (in N);

d1 and d2 Lateral dimensions of the cross-section (in mm);

L Distance between the supporting rollers (in mm).

From the results got from the test, a load vs deflection graph was plot and the elastic modulus of each

kind of beam was calculated from the formula:

𝐸 = [23 × 𝑊 × 𝐿3]

[ 648 × 𝛿 × 𝐼] (5)

where:

W Load

L Length of the beam

δ Deflection

I Moment of inertia.

Now,

𝐼 =𝑏𝑑3

12 (6)

where:

b Width of the beam

d Depth of the beam

3.0. Results

3.1. Absorption test result

The absorption test result is shown in Table 3 below, while the graph showing the relationship

between percentage of water absorbed and number of nodes is shown in Figure 5.

Table 3: Absorption test result Specimen No. of nodes Dry weight (g) Saturated weight (g) Water absorbed after

24hrs (g)

% of water absorbed

(by sat. wt.)

A1 1 55 72 17 23.61%

A2 2 115 155 40 25.81%

B1 1 115 135 20 14.81%

B2 2 150 180 30 16.67%

Figure 5: Graph of % of water absorbed vs number of nodes

0

5

10

15

20

25

30

1 NODE 2 NODES

% O

F W

ATE

R A

BSO

RB

ED (

BY

SA

TUR

ATE

D W

EIG

HT)

NUMBER OFNODES

A (FROM TOPPART OF CULM)

B(FROMBOTTOM PARTOF CULM)



Figure 5 shows that specimen with higher number of nodes absorbed a larger amount of water. The

water absorption capacity of bamboo from the top of the culm is higher than that from the bottom of

the culm. We see an additional increase of about 9%.

Generally, from the experiment done, it is seen that the water absorption capacity of bamboo is high

ranging to about 25% of saturated weight in just 24 hrs. This shows that there is a high possibility of

swelling of the bamboo splints once they absorb water from the surrounding, eventually generating

additional stresses in reinforced concrete elements if used as reinforcing material. It could also absorb

and reduce a part of the water added in the concrete mix for hydration reactions and when the

concrete becomes dry the bamboo splints contracts and creates spaces between the bamboo and

concrete and the bamboo-concrete bond strength decreases and member fails in bond.

3.2. Tensile test result

Tensile tests were conducted on bamboo samples from different part of the culm and with different

nodal position to find a pattern of behaviour based on the structure of Bamboo as a plant. The result of

the tensile test (shown in Table 4) showed a pattern of failure. The samples failed at the node. Figure

6 shows four different test specimens after failure at the nodes.

Figure 6: Failure patterns of bamboo specimens.

It was also observed that the samples with centre nodes held a larger load before reaching failure in

contrast to those without a node. Examination of the node structure shows that the fibres in the nodes

are much denser than those of the internodal regions. Also, the fibres which are straight elsewhere

become chaotic in the node. Tests and study of Bamboo nodes indicate that the node may be very

brittle and stiff, suggesting the reason why the specimen fails at the nodes. Test sample suggested the

internodal regions of the Bamboo elongated until it reached a limiting value and then the load was

transferred to the node.

The test results also showed that samples from the bottom of the culm generally held larger load

before failure in contrast to those from the top part of the culm.

Table 4: Tensile test result Sample Failure Load

(N)

CSA (mm2) L (mm) Δ L (mm) Stress

(N/mm2)

Strain

A1t 18000 225 540 10 80.00 0.0185

A2t 16000 205 540 9 78.05 0.0167

B1t 37000 435 450 15 85.06 0.0333

B2t 34000 435 450 13 78.16 0.0289

A sample test result is summarized in Figure 7.



Figure 7: Graph of stress vs strain

It seems that constitutive relationship of the nodes differs from those of internodal regions with nodes

having a brittle behaviour while internodal regions exhibit a more ductile behaviour. However, the

ultimate strength of the node is anticipated to be higher than other regions.

The yield stress of the Bamboo strip is 56.80 N/mm2.

The modulus of elasticity is calculated as follows:

𝐸 = 𝜎

휀

σ = 56.80 N/mm2, ε = 0.0015.

Thus,

𝐸 =56.80 / 0.0015

E = 37,866.667 N/mm2

The Modulus of Elasticity of the Bamboo strip is 37,866.667 N/mm2.

3.3. Flexural test result

The beam was carefully placed under the testing machine and supports were placed at the measured

location of 150 mm inside from each end. After placing the beam, one point loading at the mid-span

of the beam was applied gradually. The deflection of the beam at mid- span was measured at regular

interval of loading. From the experimental test the load deflection graph, ultimate carrying capacity

and the type of failure were recorded.

3.4. Comparison of modulus of elasticity of singly reinforced and doubly reinforced Bamboo beams

Based on the experimental study the modulus of elasticity of Doubly Reinforced Beam is about 160%

that of the Singly Reinforced Beam (see Table 5). The comparison is also shown in Figure 8. Modulus

of elasticity for Singly Reinforced Beam is 8,246.04 N/mm2. Modulus of elasticity for Doubly

Reinforced Beam without steel stirrup is 12,422.84 N/mm2 and with steel stirrup is 13,094.81 N/mm

2.

0

10

20

30

40

50

60

70

80

90

0 0.02 0.04

STR

ESS

(N/m

m2 )

STRAIN



Table 5: Modulus of elasticity and flexural strength for the different types of beams Load, W(KN) Deflection, δ (mm) Modulus of elasticity, E

(N/mm2)

Flexural strength,

Fcf (N/mm2)

Plain concrete 18 0.87 7,343.6 2.4

Singly reinforced with

bamboo

23 0.99 8,246.04 3.1

Singly reinforced with steel 50 1.08 16,432.33 6.7

Doubly reinforced with

bamboo without stirrups

35 1.00 12,422.84 4.7


steel without stirrups

59.8 1.12 18,951.17 8.0


bamboo with steel stirrups

38 1.03 13,094.81 5.1


steel with steel stirrups

62 1.15 19,135.80 8.3

Figure 8: Comparison of modulus of elasticity for Bamboo reinforced beams

4.0 Conclusion

This work provides bamboo as a potential reinforcement in concrete beams. Bamboo has excellent

engineering properties and can be utilized for low cost housing project. It can mainly be used as

reinforcement to the structure. Drawback of bamboo as construction material is its water absorption

and moisture content properties. This mainly affects its strength. To reduce this effect, seasoning and

proper coating to bamboo should be done before using it for reinforcement. After the experiment, the

following conclusions were made:

1. Water absorption of bamboo is quite high. To reduce this effect, seasoning or other suitable

treatment should be given.

2. Tensile strength of bamboo is good and can be used as reinforcement in R.C. structure for low

cost housing project. From stress-strain curves of bamboo, it can be seen that bamboo

possesses low modulus of elasticity compared to steel. So, it cannot prevent cracking of

concrete under ultimate load. But from the flexural test of bamboo reinforced beam, it has

been seen that using bamboo as reinforcement in concrete can increase the load carrying

capacity of beam having the same dimensions.

3. The stress-vs.-strain curve of bamboo splint in tension shows that bamboo is a visco elastic

material having both viscous and elastic properties and exhibits time dependent strain

elasticity.

4. Bamboo shows ductile behaviour as in steel. Hence it can be used as compression members in

steel as well as R.C. structure.

5. For bamboo reinforced concrete beam, the load carrying capacity increased about 2 times that

of plain concrete beam having same dimensions.

0

2000

4000

6000

8000

10000

12000

14000

singlyreinforced

doublyreinforced

withoutstirrups

doublyreinforced

withstirrups

MO

DU

LUS

OF

ELA

STIC

ITY



6. The flexural strength of bamboo reinforced beam increases as high as nearly doubled

compared to the plain concrete beam, so bamboo reinforced beam can be used in low cost

buildings.

7. The maximum deflection of bamboo reinforced concrete beam is about 1.5 that of plain

concrete.

This study concludes that it is possible to use bamboo as reinforcing for masonry structure.

References

Bhonde, D., Nagarnaik, P. B., Parbat, D. K. and Waghe, U. P. (2014). Experimental investigation of

bamboo reinforced concrete slab. American Journal of Engineering Research 3(1), pp. 128-131.

BS 1881-183:1983 Testing concrete. Method for determination of flexural strength. BSI, Brussels.

Sakaray, H., Vamsi Krishna Togati, N.V. and Ramana Reddy, I.V. (2012). Investigation on properties

of bamboo as reinforcing material in concrete. International Journal of Engineering Research and

Applications, 2, pp. 1-5.

Salau, M.A., Adegbite, I. and Ikponmwosa, E.E. (2012). Characteristic strength of concrete column

reinforced with bamboo strips. Journal of Sustainable Development, 5(1), pp. 133-143.

Siddhpura, N.B., Deep B.S., Kapadia, J.V., Chetan, S.A. and Sevalia, J.K. (2013). Experimental study

on flexural element using bamboo as reinforcement. International Journal of Current Engineering

and Technology 3(2), pp. 476-483.

Steinfeld, C. (2001). A Bamboo Future. Environmental Design and Construction. Available at:

http://www.edcmag.com/CDA/ArticleInformation/features/BNP_Features_Items/

Wakchaure, M. R. and Kute, S.Y. (2012). Effect of moisture content on physical and mechanical

properties of bamboo. Asian Journal of Civil Engineering (Building & Housing) 13(6), pp. 753-763.

http://www.edcmag.com/CDA/ArticleInformation/features/BNP_Features_Items/

evaluation of the feasibility of the use of bamboo as potential … · 2019-03-20 · concrete...

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